US2125055A - Control system - Google Patents

Description

July 26, 1938. w. R. TALIAFERRO CONTROL SYSTEM Filed April 24, 1935 3 Sheets-Sheet l INVENTOR 6, 1938. w. R. TALIAFERRO 2,125,055

CONTROL SYSTEM Filed April 24, 1955 3 She ets-Sheet 2 M M 0 0 4M 4 M M M 4 m 7 an 7 4 y l938w w. R. TALIAFERRO 2,125,055

CONTROL SYSTEM Filed April 24, 1935 3 Sheets-Sheet 3 WlTNESSES: INVENTCR '20 "other objects of my invention will be explained which is carried by a contact block 21 secured to Patented July 26, 1938 UNITED STATES BATENT QFFlCE CONTROL SYSTEM William R. Taliaferro, Pittsburgh, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa", a corporation of Pennsylvania Application April 24, 1935, Serial No. 17,969 3 Claims. (01. 171-229) My invention relates, generally, to control syscopper or other non-magnetic material. The cup terns, and, more particularly, to systems for con- \I5 is concentric with the magnet l0, and is cartrolling the operation of electric motors. ried by a short shaft l6 which is mounted in An object of my invention, generally stated, is bearings l1 and IS. The bearing I8 is sup- 5 to provide a motor control system which shall be ported by a frame member 2|, which is secured simple and eflicient in operation. and which may to the frame member l3 by screws 22, and the .be economically manufactured and installed. end bearing 11 is supported by a bracket 23, se-

A more specific object of my invention is to cured to the frame member 2| by screws 24. A

provide a relay for controlling the operation of laminated steel ring 25, which surrounds the 10 an electric motor which shall be responsive to the magnet lo and the cup I5, is clamped between 10 speed of the motor. the frame members 13 and 2|, thereby prodiding Another object of my invention is to provide a magnetic circuit for the flux of the magnet IO. for remotely varying the setting of a speed-re- As will be readily .understood, eddy currents sponsive relay. I are produced in the cup 15 and the rotation of A further object of my invention is to provide v the magnet l produces a magnetic drag or 15 a system for regulating the speed of an electric torque on the cup, the torque being approximotor; mately proportional to the speed of rotation of A still further object of my invention is to prethe ma t U- Ho e p rotation o vent hunting of a speed regulating system. the cup is prevented by a contact arm 26,

fully hereinafter or' will be apparent to those the shaft IS. The contact arm 26 is disposed beskilled in the art. I tween fixed contact members 28 and 29, which For a fuller understanding of the nature and are mounted on the stationary frame members. objects of my invention, reference may be hadw A calibrating sp 3| is disposed to pp the 15 to the following detailed description taken in torque on the cup 15, thereby biasing the con:g,

v conjunction-with the accompanying drawingsin tact arm 26 against the upper contact member which: L 28 when the rotating magnet is driven below Figure 1 is a view, in elevation, of a speed-rea predetermine'd speed. When the torque prosponsive relay constructed in accordance with duced by the magnet to on the cup is suflicient rm my invention; to overcome the force of the spring 3|, the con- Fig. 2 is a view, in section, of the relay shown tact arm 26 is actuated. into engagement with .in Fig. 1; the contact member 29. Therefore, it will be Fig. 3 is another view, in elevation, of the reseen that the device is responsive to the speed lay illustrated in Figs. 1 and 2; of the apparatus driving the rotating magnet l0 r Fig. 4 is a view, partly in section and partly in and that it may be utilized as a sp r l and elevation, of a modification of the relay shown in also s a speed regulator, as Will he more fully Figs. 1, 2 and 3; I explained hereinafter.

Fig. 5 is a view, in section, taken along the line In the modificatieh 0f the relay Shown in Figs, V-V of Fig. 4; and r 4 and 5, the laminated ring 25 is omitted and a 40 Figs. 6, 7 and 8 are diagrammatic views of conp 35 ompo ed of ama n tic'm ri l. u h as trol systems embodying my invention. a Steel, is utilized, thereby providing a path for the Referring 'now to the drawings and partieumagnetieflux produced by the rotating magnet larly to Figs. 1, 2 and 3, the speed-responsive re- 10: A thin layer 35 of copper, or other nonlay shown therein is of the magnetic drag type magnetic material, 18 p d n the inside of and comprises a' rotating magnet II) which is t e m of th D s the laminated ring 45 mounted on the end of a shaft H by means of 15 d D the Structure s w in Figs: stud bolts l2.- The shaft l,l isrotatably supported 2 and 3, are combined into 35 8 r. in a frame member H! by a sleeve bearing l4 and e y Simplifying the. structure. 5 'the shaft may be either directly connected or The p 35 is carried yt shaft rotfltably geared to an electric motor, locomotive axle or mounted in a supporting frame 31, which may be 50 other rotating apparatus, whose speed it is debolted onto an end bracket 38 of an lectricmosired to regulate or utilize as a means of contor by stud bolts 39. The magnet It! may be setrolling the operation of other equipment. cured to the end of the motor shaft (not shown).

As shown, the magnet I0 is disposed insideof by stud bolts 40, the magnet shaft ll being dis- .a cup l5, which may be composed of aluminum,- posed at the center of the motor shaft. In this 55 manner the relay may be rigidly secured to an electric motor, or other apparatus having a rotating shaft, the relay magnet being "driven at the same speed as the shaft of the motor.

As shown in Fig. 4, the contact members 4|, 42, 43 and 44 are carried by the contact block 21, which is secured to the shaft N5 of the cup 35 and actuated thereby. The contact members 4|, 42, 43 and 44 are normally biased by a compression spring 45 into engagement with contact members 46, 41, 48 and 49, respectively, which are resiliently mounted on the stationary frame 31.

The spring 45 functions similarly to the spring 3| to oppose the torque on the cup 35 and bias the contact members of the relay to predetermined positions. The spring may be calibrated by means of an adjusting screw 5|, thereby varying the speed at which the rotating magnet I6 must revolve in order to produce suflicient torque dirt.

to'overcome the spring and operate the cup 35. A stop member 52 is provided for limiting the travel of the cup 35. The, relay is totally'enclosed by a cover 53 for protection against moisture and Further protection is aiiorded by a felt liner 54. 5

As illustrated in Fig. 6, the speed-responsive relay herein described may be utilized to open the circuit through the starting winding of a singlephase induction motor 66 when the motor has attained a predetermined speed. The motor 66 is provided with a starting winding 6| which may be connected across the power conductors 62 and 63 by means of a starting switch 64 to start the motor. When the line switches 65 and 66 are closed to connect the conductors 62 and 63 to any suitable source of alternating-current power, the actuating coil 61 of the starting switch 64 is energized through a circuit established by contact members 26 and 28 ofthe relay, which are biased to their closed position by the spring 3| on the speed-responsive relay.

As described hereinbefore, when the motor attains a predetermined speed, the torque developed by the relay is sumcient to overcome the force of the spring 3| and the contact members 26 and 2B are opened, thereby deenergizing the actuating coil 61 of the starting switch 64, which permits the switchto open and disconnect the starting winding 6| of the motor 60.

Centrifugally-operated switches have been utilarge motors. It is apparent that the speed-re sponsive relay herein disclosed may be utilized with a motor of any size, and that it may be built at a comparatively small cost. Furthermore, the speed setting of the relay may be readily adjusted by means of the calibrating spring 3|, thereby permitting the relay to becalibrated to dee'nergize the starting winding at the'most-suitable speed for the particular motor being controlled by the relay. 1

As shown in Fig. 7, the speed relay may also be utilized to control the relative values of resistance and reactance 'in a shunt 1| for the interpole winding 12 of an alternating-current motor 13, of the commutating type. In order that satisfactory commutation of the motor 13 may be obtained at various operating speeds, it is necessary to vary the relative values of resistanceand reactance in the-interpole shunt 1|, as is fully described in Patent No. 1,922,724, issued August 15, 1933, to S. H. Cowin and L. J. Hibbard. The shunt 1| includes a reactor 14 and resistors 15 and 16, which are connected in series circuit relation with the reactor 14. -As shown, an elec- 5 tlcally-operated switch 11 is provided for short circuiting the reactor 14 when the switch 11 is in the deenergized position. When the actuating coil 18 of the switch 11' is ener'gized,'the reactor 14 is connected in the shunt circuit, and the resistor is short circuited from the interpole shunt 1|, thereby varying the relative values of resistance and reactance in the shunt for the interpole winding 12.

Assuming that the motor 13 is operating at a 15 relatively low speed, the contact members 26 and 29 of the speed relay are separated by the spring 3| and the actuating coil 18 of the switch 11 is deenergized. When the motor- "attains a predetermined speed, the contact members 26 and 29 are closed by the torque producedby the rotating magnet of the relay, as herein described, and the actuating-coil." is connected across a battery 19, thereby energizing-the coil and actuating the switch 11 to itsuppermost position to change the 5 relative valuesof resistance and reactance in the interpole shunt 1|.

In order that the speed at which the relay operates may be remotely controlled a solenoid BI is provided on the relay to oppose the spring 3|, 30 as shown in Fig. 7. It will be understood that when the solenoid -B| is energized, less torque will be required to overcome the force of the spring 3| and permit the contact members 26 .and 29 to close. Therefore, the-relay will function to operate the switch 11 at a lower speed of the motor 13 than when the solenoid 8| is deenergized. The solenoid 8| may be energized by closing a switch 82, which may be located at ,any suitable point, thereby permitting the speed 40 setting of the relay to be remotely controlled.

'In the motor control system illustrated in Fig. 8, the relay herein described is utilized as a speed regulating device for controlling the operation of a shunt motor 85, which is provided withan armature winding 86 and a shunt field winding 61. A'sis well known in the art, the speed of an 'electric motor may be controlled by varying the current in the motor field winding. The relay is driven by the motor shaft, in the manner hereinbefore described, and the contact members of the relay are so connected in the motor circuit that the current in the shunt field winding 81 is decreased wheh the contact members 26 and 28 are closed by the spring 3|,,thereby' causing the speed of the motor 85 to increase. Referring to Fig. 8, it .will be seen that a resistor 88 is connected in series circuit relation with the field winding 81, and a resistor 89 is connected parallel to the field winding 81 when thecontaot members 26 and 28 of the relay are closed, which causes a minimum amount of current to flow through the field winding 81..

When the motor 85 attains a speed which will producesufiicient torque in the relay, in the manner hereinbefore described, to overcome the force of the spring 3| and open the contact members 26 and 28 and close .the contact members 26 and 29, the resistor 88 is shunted and resistor 69 is disconnected from the shunt field circuit and the 70 tact members 26 and 26 remain closed until opened by the spring 8|, which will decrease the motor field current and cause the motor speed to increase when the cycle of operation is again repeated. In this manner, the relay may be utilized as a speed regulator to control the speed of the motor 88.

In order to prevent hunting or surging of the regulating system, the solenoid coil 8| may be connected either in series with or parallel to the resistor 88,v as shown. Thus the coil 8| is energized when the contact members 28 and 28 are closed by the spring 8|. The circuit through the coil 8| may be traced from the power conductor 8| through the resistor 88, conductor 92, contact members 28 and 28, conductors 84 and 88, thecoil 8| and conductor 88 to the power conductor 92.

As the solenoid 8| opposes the spring 3| when energized, it will be seen that the solenoid .8| tends to prevent overshooting oi'.'the regulator, since it will cause the contact members 28 and 28 to open slightly before the motor has attained the maximum speed normally permitted by the regulator. Since the solenoid 8| isdeenergized when thecontact members 26 and 28 are opened by the torque produced in the relay as a result of the increased speed of the motor, the spring 8| is enabled to again close the contact members of the relay without having to overcome the force of the solenoid 8|.

In this manner, the speed of the motor 88 is regulated by controlling the current in the field winding 81 by means 0! the resistors 88 and 88, which are alternately connected in and disconnected from the field winding circuit by means of the contact members on the speed regulating relay, and hunting of the regulating system is reduced by the action of the electrically energized solenoid 8|. 1

From the foregoing description, it is apparent that I have provided a speed-repsonsive device regulator to control the speed or electric motors which may be economically constructed and may be readily utilized as a speed relay to control the operation for numerouselectrical or mechanical devices, and may also be utilized as a speed of various types. Y I

I! desired, the relay may be modified to constitute a speed-responsive device having a time delay characteristic by permitting the cup member 01 the relay to rotate and drive a gear train loaded with a spring or friction load. In this manner contact members or mechanical trip devices may beoperated in sequential relation by the relay within a predetermined time after the cup starts to rotate, thereby providing a time element after a certain speed is reached.

While I have illustrated the manner in which the speed-responsive device may be connected to and utilized with various electrical devices, it will be understood that it may be readily utilized in connection with mechanical apparatus, as well as electrical.

Since many modifications may be made in the apparatus and arrangement of parts without departing from' the spirit of my invention, I do not wish to be limited other than by the scope of the appended claims.

I claim as my invention:

1. Ina motor control system, in combination,

an electric motor, a field winding for said motor,

a speed-responsive relay having a rotating member driven by said motor, a rotatablemember magnetically actuated by the rotating member, spring means for governing the movement of the rotatable member to control the current in the 1 motor field winding, thereby regulating the speed of the motor, and electro-magnetic means controlled by said rotatable member to vary the effect of said spring means.

2. In a-motor control system, in combination,

.an' electric motor, a field winding for said motor,

a speed-responsive relay having a rotating member driven by said motor, a rotatable member magnetically actuated by therotating member,

' spring .means for biasing the rotatable member to shunt the motor field, thereby regulating the speed of the motor, electro-magnetic means disposed to vary the eflect of said spring means, and means actuated by said rotatable memberfor controlling the energization of said electro-magnetic means.

3. In a motor control system, in combination, an electric motor, a field winding for the motor, a speed-responsive relay} having a rotating member driven by said motor, a rotatable member magnetically actuated by the rotating member to increase the'motor field current, spring means for biasing the rotatable member to decreasethe field current, thereby regulating the motor speed, electrically-energized means disposed, to, oppose the spring means to prevent hunting of the regulating system, and means actuated by said rotatable member for controlling the energization of said electrically energised means.

WIILIAKR.

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